The current microbiology/infectious disease literature states that prognosis and therapy of cryptococcal meningitis are directly related to the titers of cyrptococcal antigen found in the cerebrospinal fluid and that at the end of therapy, the cryptococcall antigen titer should be approaching zero. The aforementioned is based upon data derived at NIH using a commercially unavailable research assay for the determination of cryptococcal antigen titers. Recent personal communications from outside institutions of titers in treated patients exceeding 1:4000 and as high as 1:41,000 using commercial antigen kits have created concern among clinical pathologists and infectious disease clinicians. In a number of cases prolonged antifugal therapeutic courses have been administered because of the persistent high titers. We will determine cerebrospinal fluid cryptococcal antigen titers using three cryptococcal antigen titers and the clinical and microbiological status of the patient.